package com.xzy.h;

import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.FactoryBean;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.beans.factory.config.BeanPostProcessor;
import org.springframework.beans.factory.config.InstantiationAwareBeanPostProcessor;

import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;

/**
 * 说明：基于BeanPostProcessor模拟实现AOP
 *
 * @author xzy
 * @date 2021/12/5 20:22
 */
@Slf4j
public class MyAopBeanPostProcessor implements BeanPostProcessor {
    /**
     * Apply this {@code BeanPostProcessor} to the given new bean instance <i>after</i> any bean
     * initialization callbacks (like InitializingBean's {@code afterPropertiesSet}
     * or a custom init-method). The bean will already be populated with property values.
     * The returned bean instance may be a wrapper around the original.
     * <p>In case of a FactoryBean, this callback will be invoked for both the FactoryBean
     * instance and the objects created by the FactoryBean (as of Spring 2.0). The
     * post-processor can decide whether to apply to either the FactoryBean or created
     * objects or both through corresponding {@code bean instanceof FactoryBean} checks.
     * <p>This callback will also be invoked after a short-circuiting triggered by a
     * {@link InstantiationAwareBeanPostProcessor#postProcessBeforeInstantiation} method,
     * in contrast to all other {@code BeanPostProcessor} callbacks.
     * <p>The default implementation returns the given {@code bean} as-is.
     *
     * @param bean     the new bean instance
     * @param beanName the name of the bean
     * @return the bean instance to use, either the original or a wrapped one;
     * if {@code null}, no subsequent BeanPostProcessors will be invoked
     * @throws BeansException in case of errors
     * @see InitializingBean#afterPropertiesSet
     * @see FactoryBean
     */
    @Override
    public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
        if (bean.getClass().isAnnotationPresent(MyAop.class)) {
            ClassLoader classLoader = bean.getClass().getClassLoader();
            Class<?>[] interfaces = bean.getClass().getInterfaces();

            return Proxy.newProxyInstance(classLoader, interfaces, new InvocationHandler() {
                @Override
                public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
                    log.info("代理逻辑1");
                    method.invoke(bean, args);
                    log.info("代理逻辑2");
                    return null;
                }
            });
        }

        return bean;
    }
}
